1993 Chevy Astro Van died out.

My wife added some oil in the family van on a Fri morning. I drove the van Sat night and as I was driving I noticed the car pulling a bit, but she said she added oil because it felt funny. To make a long story short, after pulling up in our driveway, the van just cut off. I started it again, but it died after I let go of gas. I raised the hood to the engine, and sure enough - she left the oil cap off. The van will not start now, but it tries to turn over. I have only tried it about 3 times since it stopped to minimize any FURTHER damage, but I am trying to get a good answer before I take it to the mechanic and get his overpriced assessment.
Please Help